Perry's Index to the Aesopica

Fables exist in many versions; here is one version in English:

THE LEOPARD AND THE FOX

The leopard, renowned for his spots and the fine fur of his chest, went out
into the fields together with the other animals. As the coats of the mighty
lions were all one colour, the leopard quickly concluded that the lions must
be a wretched species indeed. Scorning the rest of the animals for their slovenly
appearance, the leopard considered himself to be the only true example of nobility
among them. As the leopard was rejoicing in the novelty of his apparel, the
sly fox criticized him sharply and showed how useless his markings were. 'Go
ahead and put your faith in the excessive embellishment of your youth,' said
the fox, 'so long as my intelligence is more attractive than yours: after all,
mental endowments are more impressive than the glamour of good looks!'

Source:
Aesop's Fables. A new translation by Laura
Gibbs.
Oxford University Press (World's Classics): Oxford, 2002.
NOTE: New
cover, with new ISBN, published in 2008; contents of book unchanged.

You can find a compilation of Perry's index to the Aesopica in the gigantic appendix to his
edition of Babrius and Phaedrus for the Loeb Classical Library
(Harvard University Press: Cambridge, 1965). This book is an absolute must for anyone interested
in the Aesopic fable tradition. Invaluable.